Allow mocking of enum element-methods with @Mocked, without requiring @Capturing

[rliesenfeld]

Enum types with per-element methods currently can only be mocked with @capturing, because of the fact that the compiler puts those method implementations into subclasses of the enum.

This is not obvious to the user, and must be avoided; use of @mocked should be enough in this case as well.

[rliesenfeld]

Done.